In the fall of 1926, itinerant laborer Judd McCarthy disappears with a company payroll while traveling between two small towns in the Midwest. Thirty-three years later another man, lawyer Joel Hampton, thinks he is going insane. Victimized by nightmares and blackouts, Joel is prone to sudden, unpredictable violent outbursts. Psychiatrist Ned Finley, who becomes involved in the case, believes that Joel's problems defy traditional psychological explanations. Under hypnosis, Joel expresses memories that appear to belong to another person. Finley consults with his good friend Aurther Schlepler, a reluctant psychic who once worked with police departments to solve difficult homicide cases. Schlepler has taken up permanent residence in the Farmington State Mental Hospital to avoid "the truly insane who live on the other side of Farmington's massive walls." With Schlepler's assistance, Finley starts to peel away Joel's suppressed memories. Under hypnosis, Joel remembers a time when he apparently lived in Carver County in 1926 and knew a woman by the name of "Katharine." However, Joel's wife Susan informs Finley that her husband was not born until 1927. As Joel's violent outbursts steadily worsen, Finley becomes convinced that his patient is slowly being possessed by the spirit of a man who was prone to violence and once lived in Carver County. Finley eventually journeys to the small town of Danvers, where he learns of a man who disappeared in 1926 while transporting a company payroll between two small towns. As Finley struggles to learn what happened to Judd McCarthy, and why his spirit seemingly lives on in Joel Hampton, his own life is threatened by some menacing presence in the small town. Meanwhile, Joel, who has fully assumed the persona of Judd McCarthy, remains under sedation at the mental hospital, where he plots an escape and dreams of the mysterious Katharine who lives on in his memories.